Preparations at McGill College, Montreal, for observing the Transit of Venus, December 6th, 1882. By ALEXANDER JOHNSON, M.A., LL.D., Dublin, Professor of Mathematics and Natural Philosophy.

(Abstract.)

At the time of the transit of 1874 McGill College was very poorly supplied with astronomical instruments. It had a refracting telescope of 2 inches aperture, which together with a small transit instrument and a chronometer for taking time observations, constituted practically its whole equipment. In order to call public attentton to our wants, I wrote a letter, therefore, to one of the daily papers, pointing out the importance of the coming transit of 1882 and the need of proper instruments to observe it, but this had no immediate effect. About the end of the year 1878 some of the citizens of Montreal who felt an interest in astronomy held two or three private meetings to consider the possibility of establishing a public Astronomical Observatory as an independent institution, governed by trustees. In accordance with a request from them, I wrote a letter on the subject which was inserted in the newspapers in January, 1879, and in this I again directed attention to the approach of the great astronomical event.

In September, 1879, Mr. Blackman, B.A., of Yale College, U.S., then a resident of Montreal, made a very handsome donation to the College of astronomical instruments, including a 6 inch equatorial of 7 feet focal length, a large transit instrument, an excellent mean time clock, a sidereal clock and chronometer.

Subsequently, two good but smaller telescopes of 41 and 4 inches aperture were placed in the College, one left to the Trafalgar Institute by the late Donald Ross, and committed for safe-keeping to McGill College, and one lent by G. A. Drummond, Esq. As far as instruments sufficient for Transit observations were concerned, the College was now well supplied; for, with no very great addition, it could have equipped two or three observing stations, besides Montreal. But these other stations would have involved considerable expense, and it was necessary to provide for this. To allow so much "observing plant" to lie unused would not have been creditable to the city. In February, 1880, I read a paper before the Athenæum Club of Montreal explaining the state of the case, and afterwards another paper on the same subject in May, 1881. Subsequently the question was taken up by the Corporation of the College and a committee was appointed to consider the means of providing for the expenses and other matters. In their name I wrote to the Astronomer Royal, explaining our situation and asking for information as to the expenses of stations in 1874, and advice and instructions generally The letter was submitted by him to the Committee of the Royal Society who had charge of the arrangements for all the British Transit of Venus expeditions; and in his reply he gave ample information, which was of great service, in addition to sending the report of the British Observations of 1874, which had not long been published, together with the "Instructions to Observers" in that year. At a later period, five copies of the "Instructions" for 1882 were sent out. Questions of expense were

set at rest to a great extent, though not wholly, by the money grant made in April, 1882 (I think), by the Dominion Parliament for observations in Canada generally. The administration of this grant was placed in the hands of Mr. Carpmael, Superintendent of the Meteorological Service, Toronto. By means of this grant it was possible to establish a station at Winnipeg, where Prof. McLeod (Superintendent of the Meteorological Observatory, McGill College) subsequently took observations, using the Ross telescope, described above, among other instruments. Another McGill College telescope (the Drummond), and a transit instrument (the latter of which, however, was subsequently not required), were sent to Ottawa for the use of the observers stationed there. But these instruments did not leave the College until October or November. Before that time a good deal of work had been done, in the observers' training especially.

The "model" which had been obtained from England by Mr. Carpmael, through Lieut. Gordon, had been sent up on the cupola of the College, and "model practice" had been carried on systematically. The observers at first were Dr. Jack, of New Brunswick, Mr. Carpmael, Prof. McLeod and myself. Subsequently we had the McGill College observers only who are mentioned farther on.

When this "model" was removed to Toronto for use by other observers assembled there, another model made in Montreal after the same pattern was substituted for it, and with this, practice was continued from time to time. An exact determination of the longitude being of great importance, it was resolved to check that previously adopted, and accordingly Prof. McLeod connected the Observatory by triangulation with a post of the U.S. Coast Survey which was not very far off on the mountain, and by this means found the longitude to be 4" 54" 18 87 W., differing slightly from that previously used. Further determinations are yet to be made on this point by the telegraphic method, connnecting with Harvard Observatory, U.S.

[This has since been done, viz., in July, 1883, by Prof. Rogers, of Harvard, and Prof. McLeod; three night's observations having been taken simultaneously in each place; the observers then exchanging places, Prof. Rogers coming to Montreal and Prof. McLeod going to Harvard, when three more night's observations were taken. The observations altogether covered more than three weeks.]

The following statement will be sufficient as regards other arrangements. The distribution of the instruments to Winnipeg and Ottawa has already been mentioned. Prof. McLeod went to Winnipeg about the middle of November. Mr. Chandler, Mathematical Lecturer in the Faculty of Applied Science, McGill College, undertook to observe the transit at Montreal with the 2 inch telescope. Another telescope of the same size having subsequently been kindly lent by Mr. William Bell Dawson, M.A., M.E., a third observer for the Montreal station, Mr. J. R. Murray, B.A., then a fourth year student in Arts, was ready to take a share in the work.

Mr. Chandler's station was near to the reservoir, where a wooden hut had been erected for the purpose. Mr. Murray was to observe from the balcony in front of the centre building in the forenoon and from an upper room on the west side in the afternoon. The 6 inch equatorial was, of course, to be in the Observatory building, in which important alterations had been specially made. A considerable number of students had volunteered assistance in various capacities, so that the members of the three observing parties amounted to eighteen in all, including the observers.

The special distribution of work was as follows:-While the observer's entire attention was given to his telescope, an assistant at the word "count" from the observer would begin counting seconds from the chronometer; another assistant, with paper and pencil in hand sat at the table listening attentively, and at the word "now" from the observer, instansly noted the minute, second and estimated fraction of a second, as heard from the student counting. A third assistant, who also noted the time, as a check, was ready to take notes of what the observer saw, as soon as the immediate crowding of phenomena had passed away and gave an interval for description. Other assistants had other duties. There had been complete rehearsals of all that was to be done for several days before December 6th, so that every man was familiar with his special work. The chronometers, two of which had been borrowed in the city, were regularly compared with the transit clock to ascertain their errors and rates. Time signals had been exchanged with Toronto and Quebec on December 5th, and, as a check on the clock, time was also obtained from the Washington Naval Observatory at noon on December 5th, and afterwards on the 6th.

The weather was very unfavorable for many days before the 6th. Nevertheless on that day the oberving parties assembled at the appointed hour at the Observatory, compared chronometers with the clock, and went to their several stations. Nine o'clock came, and still the sun was hidden. The minutes then passed all too rapidly, until it was certain that first contact was passed. As 9h 30m approached, the intensity of expectation was greater, but the sky showed no signs of hopeful change. At length, the time for the second contact too had passed, and our only hope was that the afternoon might be better. At 10h 5m, too late to be of any service to us, the sun shone out, and Venus could be seen plainly on its disk. The afternoon was equally unfavorable with the morning and no contacts were seen. The ill-success at Montreal was compensated to some extent at the other two stations, Winnipeg and Ottawa, to which the Montreal instruments had been sent.